Fix type signature of query.wrapper

alerts/geomodel/query.py

@@ -1,7 +1,7 @@
 '''To make GeoModel code more testable, we abstract interaction with
 ElasticSearch away via a "query interface".  This is just a function that,
-called with a list of ES indices and a `SearchQuery`, produces a list of
-dictionaries as output.
+called with an ES index and a `SearchQuery`, produces a list of dictionaries
+as output.
 '''
 
 from typing import Any, Callable, Dict, List
@@ -10,7 +10,7 @@ from mozdef_util.elasticsearch_client import ElasticsearchClient as ESClient
 from mozdef_util.query_models import SearchQuery
 
 
-QueryInterface = Callable[[SearchQuery, List[str]], List[Dict[str, Any]]]
+QueryInterface = Callable[[SearchQuery, str], List[Dict[str, Any]]]
 
 
 def wrap(client: ESClient) -> QueryInterface: